This invention relates to an engine oil pan, and, more particularly, it is concerned with an improved vessel construction for accommodating engine lubricating oil, which is provided with an observation window for detecting and inspecting the level of engine lubricating oil in the vessel.
As an expedient for detecting a level of the engine oil in motor-cycles, automobiles, and so on, there have been known such one that is constructed with a window for detecting the oil level provided in one side wall portion of the oil pan in place of using the conventional oil level gauging or measuring rod, through which the oil level may be inspected.
However, the engine oil is highly susceptible of being contaminated by blow-by-gas, carbon particles, dusts from the facing of the clutch due to its wear, metal powder due to wear of gears, and so forth. Also, the engine lubricating oil is liable to be oxidized by heat of the combustion engine, and adheres onto the inner surface of the window glass for detecting the level of the lubricant. In particular, in the case of the motor-cycle, the engine lubricating oil is vigorously agitated by the speed changing (or power transmission) gears to be splashed around inside the oil pan and sticks onto the entire inner surface of the window glass for the oil level detection. Such adhesion of the engine oil also occurs due to vibration and considerable inclination of the motor-cycle body during its running. The oil as stuck onto the window glass for the oil level detection assumes a tar-like state due to heat of the engine, while it is kept adhered on to inner surface of the window glass, and rigidly stuck thereto, as the result of which the inside of the oil pan becomes hardly visible to make it inconveniently difficult to detect the level of the engine lubricating oil inside thereof.